从Java8函数创建请求范围bean

Question

@Configuration
public class RequestConfig {

    @Bean
    public Function<? extends BaseRequest, RequestWrapper<? extends BaseRequest, ? extends BaseResponse>> requestWrapperFactory() {
        return request -> requestWrapper(request);
    }

    @Bean
    @RequestScope
    public RequestWrapper<? extends BaseRequest, ? extends BaseResponse> requestWrapper(
            BaseRequest request) {
        RequestWrapper<?, ?> requestWrapper = new RequestWrapper<BaseRequest, BaseResponse>(request);
        return requestWrapper;
    }
}

@RestController
public class CheckRequestController {

    private final RequestService<CheckRequest, CheckResponse> checkRequestServiceImpl;

    @Autowired
    private Function<CheckRequest, RequestWrapper<CheckRequest, CheckResponse>> requestWrapperFactory;

    public CheckRequestController(
            RequestService<CheckRequest, CheckResponse> checkRequestServiceImpl) {
        super();
        this.checkRequestServiceImpl = checkRequestServiceImpl;
    }

    @PostMapping(value = "/check", consumes = { MediaType.TEXT_XML_VALUE,
            MediaType.MULTIPART_FORM_DATA_VALUE }, produces = MediaType.TEXT_XML_VALUE)
    public ResponseEntity<CheckResponse> checkRequest(
            @RequestBody(required = true) CheckRequest checkRequest) {

        RequestWrapper<CheckRequest, CheckResponse> requestWrapper = requestWrapperFactory
                .apply(checkRequest);
        checkRequestServiceImpl.getResponse(requestWrapper);

        return new ResponseEntity<CheckResponse>(requestWrapper.getResponse(),
                HttpStatus.OK);
    }
}

@RestController
public class CancelRequestController {

private final RequestService<CancelRequest, CancelResponse> cancelRequestServiceImpl;

@Autowired
private Function<CancelRequest, RequestWrapper<CancelRequest, CancelResponse>> requestWrapperFactory;

public CancelRequestController(
        RequestService<CancelRequest, CancelResponse> cancelRequestServiceImpl) {
    super();
    this.cancelRequestServiceImpl = cancelRequestServiceImpl;
}

@PostMapping(value = "/cancel", consumes = { MediaType.TEXT_XML_VALUE,
        MediaType.MULTIPART_FORM_DATA_VALUE }, produces = MediaType.TEXT_XML_VALUE)
public ResponseEntity<CancelResponse> CancelRequest(
        @RequestBody(required = true) CancelRequest cancelRequest) {
    RequestWrapper<CancelRequest, CancelResponse> requestWrapper = requestWrapperFactory
            .apply(cancelRequest);
    cancelRequestServiceImpl.getResponse(requestWrapper);
    return new ResponseEntity<CancelResponse>(requestWrapper.getResponse(),
            HttpStatus.OK);
}
}

  Field requestWrapperFactory in CheckRequestController required a bean of type 'java.util.Function' that could not be found.

The injection point has the following annotations:
    - @org.springframework.beans.factory.annotation.Autowired(required=true)


Action:

Consider defining a bean of type 'java.util.Function' in your configuration.

Answer 1

您引用的答案有所不同：它在声明的bean和注入的bean中使用完全相同的泛型类型：

@Bean
public Function<String, Thing> thingFactory() {
    return name -> thing(name); // or this::thing
} 

和：

@Autowired
private Function<String, Thing> thingFactory;

使用泛型类型有问题吗？我做错了什么？

Function<CheckRequest, RequestWrapper<CheckRequest, CheckResponse>> requestWrapperFactory;

Function<? extends BaseRequest, RequestWrapper<? extends BaseRequest, ? extends BaseResponse>>

@Bean
public Function<? extends BaseRequest, RequestWrapper<? extends BaseRequest, ? extends BaseResponse>> requestWrapperFactory() {
    return request -> requestWrapper(request);
}

编辑后：

我更新了第一部分以与您的更改保持一致。

现在，您的要求是声明一个函数，该函数向客户机返回具有客户机指定的泛型类型的原型bean。
这是可能的。但是为了使它简洁，您不应该使用两个bean：一个用于工厂（单例），另一个用于创建RequestWrapper对象（原型）。
由于工厂bean不允许客户机指定泛型类型，您将不得不执行不希望的uncasts。
还应该用@scope(value=configurableBeanFactory.scope_prototype)替换@requestScope，因为请求作用域bean不允许像配置类中的单例和原型bean那样可配置。
例如，使用参数或通配符不能很好

因此，其思想是声明一个原型bean，返回的泛型类型取决于参数和目标。
关于RequestConfig，现在最好将其命名为RequestFactory，因为这是它的角色。

@Configuration
public class RequestFactory {

    @Bean
    @Scope(value = ConfigurableBeanFactory.SCOPE_PROTOTYPE)
    public <T extends BaseRequest, U extends BaseResponse> RequestWrapper<T, U> requestWrapper(
            T request) {
        RequestWrapper<T, U> requestWrapper = new RequestWrapper<>(request);
        return requestWrapper;
    }

}

在控制器中插入@configurationbeanRequestFactory:

private RequestFactory requestFactory; // Change

public CheckRequestController(
        RequestService<CheckRequest, CheckResponse> checkRequestServiceImpl,
        RequestConfig requestConfig) {
    this.checkRequestServiceImpl = checkRequestServiceImpl;
    this.requestFactory = requestFactory; // Change
}

现在，只要需要，就可以用所需的RequestWrapper注入原型bean：

@PostMapping(value = "/cancel", consumes = { MediaType.TEXT_XML_VALUE,
        MediaType.MULTIPART_FORM_DATA_VALUE }, produces = MediaType.TEXT_XML_VALUE)
public ResponseEntity<CancelResponse> CancelRequest(
        @RequestBody(required = true) CancelRequest cancelRequest) {
    RequestWrapper<CheckRequest, CheckResponse> requestWrapper = 
               requestFactory.requestWrapper(cancelRequest);
     //...
    return new ResponseEntity<CancelResponse>(requestWrapper.getResponse(),
            HttpStatus.OK);
}